wm8918 Wolfson Microelectronics plc, wm8918 Datasheet - Page 51

• Manufacturer Part Number: wm8918
• Description: Ultra Low Power Dac For Portable Audio Applications
• Manufacturer: Wolfson Microelectronics plc

Production Data
RETUNE
w
TM
MOBILE PARAMETRIC EQUALIZER (EQ)
The ReTune
function of the EQ is to adjust the frequency characteristic of the output to compensate for unwanted
frequency characteristics in the loudspeaker (or other output transducer). It can also be used to tailor
the response according to user preferences, for example to accentuate or attenuate specific
frequency bands to emulate different sound profiles or environments such as concert hall, rock etc.
The EQ is enabled using the EQ_ENA bit as shown in Table 21.
Table 21 ReTune
The EQ can be configured to operate in two modes - “Default” mode or “ReTune
DEFAULT MODE (5-BAND PARAMETRIC EQ)
In default mode, the cut-off / centre frequencies are fixed as per Table 22. The filter bandwidths are
also fixed in default mode. The gain of the individual bands (-12dB to +12dB) can be controlled as
described in Table 23.
Note that the cut-off / centre frequencies noted in Table 22 are applicable to a DAC Sample Rate of
48kHz. When using other sample rates, these frequencies will be scaled in proportion to the selected
sample rate.
Table 22 EQ Band Cut-off / Centre Frequencies
Table 23 EQ Band Gain Control
R134 (86h)
EQ1
R135 (87h)
EQ2
R136 (88h)
EQ3
R137 (89h)
EQ4
R138 (8Ah)
EQ5
R139 (8Bh)
EQ6
REGISTER
REGISTER
ADDRESS
ADDRESS
EQ BAND
TM
1
2
3
4
5
Mobile Parametric Equaliser is a circuit that can be enabled in the DAC path. The
TM
BIT
BIT
4:0
4:0
4:0
4:0
4:0
Mobile Parametric EQ Enable
0
EQ_ENA
EQ_B1_GAIN [4:0]
EQ_B2_GAIN [4:0]
EQ_B3_GAIN [4:0]
EQ_B4_GAIN [4:0]
EQ_B5_GAIN [4:0]
LABEL
LABEL
CUT-OFF/CENTRE
FREQUENCY
2400 Hz
6900 Hz
100 Hz
300 Hz
875 Hz
DEFAULT
DEFAULT
01100b
01100b
01100b
01100b
01100b
(0dB)
(0dB)
(0dB)
(0dB)
(0dB)
0
EQ enable
0 = EQ disabled
1 = EQ enabled
EQ Band 1 Gain
(see Table 24 for gain range)
EQ Band 2 Gain
(see Table 24 for gain range)
EQ Band 3 Gain
(see Table 24 for gain range)
EQ Band 4 Gain
(see Table 24 for gain range)
EQ Band 5 Gain
(see Table 24 for gain range)
PD, Rev 4.0, September 2010
DESCRIPTION
DESCRIPTION
TM
Mobile” mode.
WM8918
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